Holocene Landscape Evolution of an Estuarine Wetland in Relation to Its Human Occupation and Exploitation: Waasland Scheldt Polders, Northern Belgium

Netherlands Journal of Geosciences — Geologie en Mijnbouw |96 – 1 | 35–62 | 2017 doi:10.1017/njg.2016.24 Holocene landscape evolution of an estuarine wetland in relation to its human occupation and exploitation: Waasland Scheldt polders, northern Belgium T. Missiaen1,∗, I. Jongepier2,K.Heirman1,5,T.Soens2, V. Gelorini3, J. Verniers3, J. Verhegge4 & Ph. Crombe´ 4 1 Renard Centre of Marine Geology, Ghent University, Krijgslaan 281 S8, B9000 Ghent, Belgium 2 Department of History, University of Antwerp, Stadscampus, S.R-A.112, Rodestraat 14, B2000 Antwerp, Belgium 3 Palaeontology Research Unit, Ghent University, Krijgslaan 281 S8, B9000 Ghent, Belgium 4 Department of Archaeology, Ghent University, Sint-Pietersnieuwsstraat 35, B9000 Ghent, Belgium 5 Currently at Geological Survey of Denmark and Greenland, Ø. Voldgade 10, DK-1350 Copenhagen, Denmark ∗ Corresponding author. Email: [email protected] Manuscript received: 7 October 2015, accepted: 13 June 2016 Abstract This paper describes the landscape evolution of the Waasland Scheldt polders in the north of Belgium from the Late Glacial – early Holocene to the present time, and the effects of this changing landscape on the human settlement. The regional landscape evolution has been visualised in a series of palaeogeographical maps for successive time frames. Two different map series were produced: a series of Holocene palaeogeographical reconstructions (11,000–950 cal BP) based on geotechnical, geological and archaeological data, and a series of post-Medieval landscape reconstructions (16th- to 19th-century) based on historical maps, land registers and soil data. Additional palaeoenvironmental information from fossil pollen and plant remains allowed reconstruction of the vegetation and wetland changes, particularly for the middle to late Holocene. Peat growth was the main key to understanding the landscape evolution of the Waasland Scheldt polders. Whereas the landscape evolution during the Holocene was mainly sea-level driven, the transformation of the landscape during the last millennium was largely due to human interventions. Keywords: historical maps, palaeogeography, peat growth, Scheldt estuary Introduction intensively exploited (Rippon, 2000). In Romney Marsh in SE England, one of the largest coastal wetlands in Britain, research The significance of coastal and estuarine areas for understand- has allowed reconstruction of the landscape evolution and hu- ing former human life and palaeolandscapes is now recognised man exploitation from later prehistory to the medieval period internationally. For example, in the context of present-day cli- (Rippon, 2002). In the Netherlands many studies have been mate warming and sea-level rise, the study of the response of carried out in coastal and estuarine/fluvial wetlands, ranging coastal and estuarine palaeolandscapes to postglacial sea-level from Zeeland in the southwest to the Wadden Sea area in the rise is particularly relevant (e.g. Boski et al., 2002; Woodruff north, unravelling the geographical, morphological and envi- et al., 2013). The large preservation potential of these sedi- ronmental changes of these landscapes through time and the mentary environments, on the transition of the terrestrial and impact on human occupation (e.g. Van der Spek & Beets, 1992; marine environment, makes them ideal for studying landscape Vos & de Wolf, 1993; Vos & van Heeringen, 1997; Bos et al., evolution through time. Research into the intertidal area of 2005; Hijma & Cohen, 2011;Vos&Knol,2015; Vos et al. 2015). the Severn Estuary, SW England (Bell, 2007), for instance, has In Flanders, systematic Quaternary geological, sedimentolog- provided the first human Mesolithic footprints, while in Roman ical and palaeoecological research on fluvial and coastal wet- and medieval times these dynamic estuarine landscapes were lands has been carried out for a number of decades (e.g. De C Netherlands Journal of Geosciences Foundation 2016 35 Downloaded from https://www.cambridge.org/core. IP address: 170.106.33.14, on 26 Sep 2021 at 02:43:56, subject to the Cambridge Core terms of use, available at https://www.cambridge.org/core/terms. https://doi.org/10.1017/njg.2016.24 Netherlands Journal of Geosciences — Geologie en Mijnbouw Muynck, 1976; Augustyn, 1977, 1985; Baeteman & Verbruggen, influenced by rising groundwater due to sea-level rise, which 1979; Heyse & De Moor, 1979; Baeteman 1991, 1999;Denys, turned the area into a continuously expanding peat marsh. A 1993), and many geomorphological, geological and soil maps second reason was the strong intertwining of landscape and have been made of Belgium including its wetlands (e.g. Jacobs human occupation during medieval and post-medieval times, et al., 1993, 2010; De Moor & van de Velde, 1995; Bogemans especially in view of the great inundations of the 14th–16th 1997;AGIV,2000; Adams et al., 2002). Moreover, early recon- centuries. Both direct and indirect human interventions greatly structions of the historical landscape of the Scheldt polders influenced the (often very rapid) transformation of the land- started in the 1960s (e.g. Snacken, 1964; Mijs, 1973;Guns, scape. Lastly, the Scheldt polders are under imminent threat 1975), and research on Late Pleistocene and Holocene deposits from commercial activities. Due to the continuous expansion has been carried out here since the late 1980s (e.g. Meire & of Antwerp harbour, only a relatively small part of the original Kuijken, 1988; Kiden, 1989; Verbruggen et al., 1996;Kiden Waasland Scheldt polders still remains. A new dock is planned & Verbruggen, 2001). However, systematic geoarchaeological in this area within the next few years, while on both sides of research into onshore wetlands in Flanders is quite a recent the border the coastal realignment in the Hedwige and Prosper development. Large-scale interdisciplinary wetland research in polder will affect the last relicts of this drowned landscape, the Scheldt floodplain was often conducted in anticipation of for example through local erosion of channels, but most of the large infrastructural works such as Antwerp harbour expansion area will be further covered and preserved under new estuarine (e.g. Minnaert & Verbruggen, 1986; Gelorini et al. 2003, 2006; deposits. Perdaen et al. 2004; Crombé, 2005; Deforce et al. 2005; Meers- The main objective of this paper is to map the palaeoland- schaert et al. 2006;Deforce,2011), nature development and scape evolution of the Waasland Scheldt polders from the Late water management projects (Bogemans et al., 2012; Meylemans Glacial – early Holocene to the present time. This is done on et al., 2013). two different timescales: (1) a Holocene timescale, resulting Drilling techniques for mapping and assessing the buried ar- in a series of palaeogeographical reconstructions mainly based chaeological and palaeoenvironmental heritage were applied in on geotechnical, geological and archaeological data; and (2) a Flanders for the first time in the mid-1990s, for example in the post-medieval timescale, resulting in a series of landscape re- Verrebroek dock in the Scheldt polders (Crombé & Meganck, constructions mainly based on historical maps, land registers 1996). Since then further testing mainly in the Scheldt flood- and data of the soil mapping. Where possible, palaeolandscape plain and polders has resulted in more refined drilling tech- reconstructions are also included, based on various environmen- niques and methods (e.g. Bats, 2007; Crombé & Verhegge, tal data (pollen analyses, plant remains, etc.). By combining 2015). Recently, a new step forward was taken in prehistoric these different techniques and methodologies we were able to landscape reconstruction for archaeological purposes with the obtain a coherent picture of the drowning of the dynamic land- PhD research by Verhegge (2015). He developed an efficient scape of the Waasland Scheldt polders since the Late Glacial, approach based on near-surface geophysical and geotechnical and the effects of this drowning on the successive stages of techniques to map the prehistoric landscape of the Scheldt human settlement and land-use through time. polders, and modelled the peat growth and the subsequent drowning of the landscape. However, his research only focused on a small test area (Doelpolder Noord), and a broader regional Study area approach was still lacking. A second new development was the reconstruction of intertidal landscape response since the 16th General background century by Jongepier et al. (2015a, b). Previously this had only been attempted on short timescales, mostly less than 100 years. The Waasland Scheldt polders consist of a flat, low-lying re- Using a combination of historical maps and analysis of present- gion on the western bank of the river Scheldt, in NW Belgium day soil texture this allowed mapping of the step-wise evolution (Fig. 1). The western and eastern limits of the study area are (location of tidal channels, tidal flats and salt marshes) over respectively formed by the Dutch/Belgian border and the river the last c. 400 years of the Waasland Scheldt polders marked Scheldt, with its southern limit situated at the edge of the by de- and re-embankment (Jongepier et al., 2015b). Waasland subcuesta. The current landscape of the Waasland The Waasland Scheldt polders were selected as the study Scheldt polders is highly influenced by the proximity of the area for three reasons. First, they are known to be rich in well- North Sea and the river Scheldt. The delicate balance between preserved prehistoric sites

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